Brake



July 12, 1938. H. T. PFEn--f--ER- BRAKE Filed Jan. 5, 1938 2 Sheets-Sheet 1 H. `T. PFEIFFER BRAKE July 12, 1938.

Filed Jan. 5, 1938 2 'Sheets-Sheet 2 gwoon/(wo www.; I

UNITED STATES PATENT lOFFICE BRAKE Howard T. Pfeiffer, Woodlawn, Md. Application January 5, 1938, lSerial No. 183,554

4 Claims.

The present invention relates to brakes, and primarily to an hydraulic brake provided with auxiliary means for optionally mechanically applying the brake shoes.

More particularly the invention pertains to hydraulic brakes, and to means for preventing the collapse of the movable rubber piston cups of the motor cylinders which move the brake shoes into engagement with the brake drum, the latter being located on a vehicle wheel.

It is now common practice in various popular makes of automobiles to employ hydraulic brakes and to provide mechanical means for optionally operating the brake shoesof the rear brakes, said mechanical means being operated by the hand or emergency brake lever. With such an arrangement it has been found that air leaks into the hydraulic system and it is the primary object of thisinvention to cure this defect.

Other aims and objects will be apparent from tlie detailed description hereinafter appearing, when taken in conjunction with the appended drawings, to whichreference is now made, and in which: l

Fig. 1 is an elevational View, partly in section, showing a brake operating motor cylinder and adjacent mechanism, as now commonly employed.

Fig. 2 is a view similar to Fig. 1 with the invention applied thereto. i

Fig. 3 is an elevational view of another type of brake also now commonly employed.

Fig. 4 is a view similar to Fig.fj3 with a modified form of the invention applied thereto, and,

Fig. 5 is a side elevational view of one of the spring pressed keeper plates employed in the construction of Fig. 4. f

In `an hydraulic brake system it is desired at all times to have suicient pressure within the system to prevent air being drawn therewithin. It is now customary in various hydraulic brake systems to actuate the brake shoes of the rear wheel brakes by a series of levers and cables controlled'by the hand or emergency brake lever. In actuating the brake shoes by this means,

which is independent'of the hydraulic system,`

there is left no support for the movable rubber piston cups normally employed in the motor cylinder wihich hydraulically operates theA brake shoes. vThese cups are forced outwardly by a spring positioned therebetween, thus causing reduced pressure within the hydraulic system and bringing about a collapse of the aforementioned rubber piston cups. When this occurs air will seep into the hydraulic system causing reduced will move these covers by actuating the pistons (Cl. 18S-152) efciency of the brakes and the frequent necessity of adjusting, that is bleeding, the system.

Referring first to Fig. 1 of the drawings there is shown a portion of the hydraulic system, namely the motor cylinder Ill, the two oppositely dis- 5, posed movable rubber piston cups ll and I2 and the interposed spring i3. In contact with the rubber piston cup H is a piston member I4, and in contact with the piston cup l2 is a similar piston member l5. 'Ihe opposite ends of the cylinder iii are provided with apertured caps or covers i6 and il. Threaded within the cover i6 is a rod I8 provided with a slot within which the brake shoe i9 loosely engages, the latter having a brake lining 2li for engaging the brake drum 2l. Similarly the c ap il threadedly engages a rod 22, which latter has a slot into which the brake shoe 23 loosely lits. kThe cap I6 is provided with an adjusting disc 2t and the cap I'l with a similar adjusting member 25. 'Ihe construction so far described is that of a well-known motor cylinder operating mechanism of an hydraulic brake system.

The brake shoes i9 and 23 are adapted to be operated by mechanical means comprising a lever 6a pivoted to brake shoe 23 at 6b. One end of a rod 6 is pivoted to brake shoe i9 as at 6c, the opposite end of rod t being provided with a slot within which the lever 6a loosely nts. Upon actuation of the lever 68 to the right, as viewed 3o in Figs. 1 and 2, there follows a-spreading of brake shoes i9 and 23.y When this occurs there will be no means preventing outward movement of the cylinder covers I6 and I1. VThe springl M and i5. This produces a reduced pressure within the hydraulic system and causes av collapse of the rubber piston cups Il and I2 so that air will seep into the system around the end edges of lthe cylinder l@ and about the collapsed 40 rubber piston cups. By referring to Fig. 2 of the drawings it will be seen that a spiral spring' 30 is provided intermediate each cylinder cover I6, Il and its brake shoe, which spring exerts a slightly greater force than the spring I3 within the cylinder lil. A centering disc 3l is employed. for holding. each spring 3D in position intermediate a brake shoe and a cylinder cover. Accordingly the springs 3U stop the tendency toward outward movement of the cylinder covers when the 50 brake shoes are mechanically actuated and thus z prevent theV collapse of the rubber piston cups, for the reasons above stated.

Referring no w to Fig. 3 there is shown in elevation another common form of brake, the brake shoes being designated by the numerals 29 and 33 and the hydraulic brake motor cylinder of internal construction as shown in Figs. 1 and 2, by the numeral 40. An adjusting screw l0 is provided for the shoes 29 and 33, and the cylinder has a pair of piston actuated rods I8 and 42 corresponding to the rods I8 and 22 of the form of the invention shown in Figs. 1 and 2. The brake shoes may be mechanically actuated by the hand or emergency brake lever of an automobile or other vehicle through the rod 5I.

For preventing the collapse of the rubber piston cups in the brake motor cylinder 40 there are provided two similar spaced oppositely disposed keeper plates 60, lillIl interconnected by a spring 6I. Each keeper plate 60, 60 is pivoted on an end of the adjusting screw as at 62, 62n and on an anchor pin 63 of the-brake. Also each plate 60, lill8L is provided with a notch 64, 64'l which receives the slotted end of one of the piston actuated rods 38`or 42. Each plate 60, 60* is outwardly offset as at 65, 6EEL to clear the rod 56 and spring 10 o'f the brake. 'Ihe force exertedby the spring 6| on the rods 38 and 42 is slightly greater than that of the spring within the cylinder 40. The keeper plates do not interfere with the normal hydraulic action of the brake shoes but upon mechanical actuation thereof movement of the piston actuated rods 38 and 42 is prevented by the force exerted by the spring il through plates 60, a.

From the above description it will be apparen that means has been provided to effectively cure a, defect in brakes actuated by combined hydraulic and mechanical means and it is contempiatcd to cover any obvious modifications of the invention as will be apparent to those skilled in the art and to be limited in this respect only as may be necessary by the scope of the claims hereto appended.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a brake mechanism, brake shoes, an hydraulic system including a cylinder having a pair of movable rubber piston cups therein, springdraulic system `including a cylinder having a pair of movable rubber piston cups therein, spring means intermediate said cups, pistons actuated by said cups, a rod actuated by each piston loosely engaging a brake shoe, means for mechanically operating said brake shoes, and spring operated means resisting outward movement of said cups upon mechanical actuation of said shoes.

3. In a brake mechanism, brake shoes, an hydraulic system including a cylinder having a pair of movable rubber piston cups therein, spring means intermediate saidcups, pistons actuated by said cups. a rod actuated by each piston loosely engaging a. brake shoe, means for mechanically operating said brake shoes, and spring means intermediate said shoes andpistonsV resisting the outward movement of said cups upon mechanical actuation of said shoes.

4. In a brake mechanism, brake shoes, an hydraulic system including a cylinder having a pair of movable rubber piston cups therein, a spring intermediate said cups, pistons actuated by said cups, a roii actuated by each piston loosely engaging a brake shoe, mns `for mechanically operating said brake shoes, and spring means exerting a greater force than said vfirst mentioned spring resisting-the outward movement of said cups upon mechanical actuation of said shoes.

HOWARD T. PFEIFFER. 

